While tacking into the wind the navigator of a sailing vessel wishes to follow the course which will allow the fastest progress in the desired direction of travel.
The optimum tacking angle for the vessel is determined by a number of variables, including wind direction and speed, water conditions, number of crew and ballast being carried. Taking these variables into account a navigator can determine the tacking angle at which fastest progress will be made.
Once the optimum tacking angle has been determined the vessels course can be plotted on a chart for the helmsman to follow.
To follow the course accurately the helmsman must know when to change tack. This point can be found by monitoring the vessel's position relative to landmarks or buoys using compasses. However, the procedure involved in taking compass bearings and converting these from magnetic to grid bearings is time consuming and, therefore, occupies a crew member who is not then available for other tasks.
It is an object of this invention to obviate or mitigate these disadvantages.